Study: Horses Prefer Nonacidic Water

Horses tend to prefer water with neutral pH levels, than low pH levels, meaning a picky drinker's problem could be due to acidic water's sour taste.

Photo: The Horse Staff

If you've been around horses long enough, you're bound to have experienced the picky drinker. Horses that are selective in their water consumption can not only be frustrating for owners, but could also be a danger to themselves, as dehydration can be a serious problem. A team of Canadian researchers, however, recently revealed that horses tend to prefer water with neutral pH levels ratherthan low pH levels, meaning your picky drinker's problem could be due to acidic water's sour taste.

"Although work has been done on the palatability by horses of specific flavors, such as peppermint and banana, there is little research available on the basic tastes," explained Katrina Merkies, PhD, a researcher at the University of Guelph's Kemptville Campus in Ontario. Merkies' graduate student, Jaime Carson, presented the results of a recent related study at the 2011 Equine Science Society Symposium, held May 31-June 3 in Murfreesboro, Tenn.

Distilled or pure water has a pH of 7 out of 14 on the pH scale (which measures how acidic, neutral, or basic substances are). For comparison, acidic water has a pH lower than 7 and has a more sour taste. Lemon juice's pH, for example, is 2 out of 14.

To determine if horses showed a strong distaste for acidic water, Merkies used 12 horses (aged 2 to 18 years) in a "random block" study design. Each horse received each treatment (water at a pH of 5, a pH of 3.6, or a pH of 2.9, adjusted by adding citric acid to the water) for four days with a two-day washout period between each different pH. Horses were also provided with "control water" that had a pH of 7.5 during each test period. Water buckets were replenished as needed, and researchers measured the amount of each type of water the horse consumed daily.

The researchers' key findings included:

There was a significant difference in the amount of water each horse consumed daily, ranging from 1.5 liters to 34.8 liters; this trend was consistent to each individual horse throughout the study;

There were no effects of age, breed, or gender noted;

All horses preferred the control water with a pH of 7.5 over the treated water;

A strong aversion to the water with a pH of 2.9 and 3.6 was noted;

A weak aversion to the water with a pH of 5 was noted; and

Although the horses had an aversion to the more acidic water, no horse completely rejected the "treated" waters.

Merkies concluded that the test horses preferred water with a neutral pH to water with a low pH and acidic taste. To her knowledge, no such tests have been carried out with basic solutions and there are no plans to do so at present ("Basic solutions tasty 'soapy,' not something that most animals would consume," she noted).

For horse owners with picky drinkers, Merkies suggests using litmus paper or a hard water test to determine if a sour acidic taste could be deterring their animals from drinking: "If the water is below 5 (in a litmus test), then it may affect water intake," she explained. "You can also use a water hardness test. The harder the water, the more basic it may be; the softer the water the more acidic it will be."

Additionally, she noted that in some instances adding a sweetener to acidic water can make it more appealing. Sweeteners can include small amounts of apple juice, cranberry juice, or Gatorade; however, it's advisable to discuss particular sweeteners with a veterinarian before using them.

"(Horses) may well choose and select specific elements to ingest according to their needs," Merkies added. "Just because the water is acidic doesn't mean it is bad for the horse. This research is only the tip of an iceberg. We know so little about what and how horses taste and what leads to horses choosing the foods they ingest.

"We do know that horses can be selective about what foods and forages they will eat and that they do prefer a variety of foodstuffs," she continued. "A better understanding of what horses do prefer will impact the feed and drug industry by being able to add flavorings--to wormers, supplements, medications for example--to make these things more palatable."

The abstract, "Discrimination of Water Acidity by Mature Horses," was published in the May/June 2011 issue of the Journal of Equine Veterinary Science.

About the Author

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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